Make error code types nodiscard

src/commit_request_parser.hpp

@@ -18,7 +18,7 @@ public:
   /**
    * @brief Status returned by streaming parse operations.
    */
-  enum class ParseStatus {
+  enum class [[nodiscard]] ParseStatus {
     Incomplete, ///< Parser needs more data to complete parsing
     Complete,   ///< Successfully parsed a complete commit request
     Error       ///< Parse error occurred (check get_parse_error() for details)
@@ -27,7 +27,7 @@ public:
   /**
    * @brief Result type for one-shot parsing operations.
    */
-  enum class ParseResult {
+  enum class [[nodiscard]] ParseResult {
     Success,      ///< Parsing completed successfully
     InvalidJson,  ///< Invalid JSON format or structure
     MissingField, ///< Required field missing from input

style.md

@@ -344,9 +344,10 @@ arena_allocator.reset();  // Reset arena memory
 - **Error messages are human-readable only** - never parse message strings
 - **Consistent error boundaries** - each component defines what it can/cannot recover from
 - **Interface precondition violations are undefined behavior** - acceptable to skip checks for performance in hot paths
+- **Error code types must be nodiscard** - mark error code enums with `[[nodiscard]]` to prevent silent failures
 
 ```cpp
-enum class ParseResult { Success, InvalidJson, MissingField };
+enum class [[nodiscard]] ParseResult { Success, InvalidJson, MissingField };
 
 // System failure - abort immediately
 void* memory = std::malloc(size);